Users Guide

Congure BFD................................................................................................................................................................ 149
Congure BFD for Physical Ports.......................................................................................................................... 150
Congure BFD for Static Routes.............................................................................................................................151
Congure BFD for OSPF.........................................................................................................................................154
Congure BFD for OSPFv3.....................................................................................................................................157
Congure BFD for IS-IS...........................................................................................................................................158
Congure BFD for BGP............................................................................................................................................161
Congure BFD for VRRP.........................................................................................................................................167
Conguring Protocol Liveness................................................................................................................................ 170
8 Border Gateway Protocol IPv4 (BGPv4)..................................................................................................... 171
Autonomous Systems (AS)............................................................................................................................................ 171
Sessions and Peers.........................................................................................................................................................173
Establish a Session................................................................................................................................................... 173
Route Reectors............................................................................................................................................................. 174
Communities............................................................................................................................................................. 175
BGP Attributes................................................................................................................................................................175
Best Path Selection Criteria.................................................................................................................................... 175
Weight........................................................................................................................................................................ 177
Local Preference....................................................................................................................................................... 177
Multi-Exit Discriminators (MEDs)...........................................................................................................................178
Origin..........................................................................................................................................................................179
AS Path......................................................................................................................................................................179
Next Hop................................................................................................................................................................... 180
Multiprotocol BGP..........................................................................................................................................................180
Implement BGP ............................................................................................................................................................. 180
Additional Path (Add-Path) Support......................................................................................................................180
Advertise IGP Cost as MED for Redistributed Routes......................................................................................... 181
Ignore Router-ID for Some Best-Path Calculations.............................................................................................. 181
Four-Byte AS Numbers............................................................................................................................................ 181
AS4 Number Representation.................................................................................................................................. 182
AS Number Migration.............................................................................................................................................. 183
BGP4 Management Information Base (MIB)........................................................................................................185
Important Points to Remember.............................................................................................................................. 185
Conguration Information..............................................................................................................................................186
BGP Conguration......................................................................................................................................................... 186
Enabling BGP.............................................................................................................................................................187
Conguring AS4 Number Representations........................................................................................................... 190
Conguring Peer Groups..........................................................................................................................................191
Conguring BGP Fast Fail-Over.............................................................................................................................194
Conguring Passive Peering................................................................................................................................... 195
Maintaining Existing AS Numbers During an AS Migration................................................................................. 196
Allowing an AS Number to Appear in its Own AS Path....................................................................................... 197
Enabling Neighbor Graceful Restart...................................................................................................................... 198
Filtering on an AS-Path Attribute........................................................................................................................... 198
Regular Expressions as Filters................................................................................................................................200
Contents
7